Articulated bending mechanism for legged mobile robot and the legged mobile robot

ABSTRACT

An articulated bending mechanism is formed by connecting links which rotatably support a plurality of gears including input-side gears and output-side gears by engaging the gears. Each link rotatably supports an odd number of gears by engaging the gears, and an output-end gear rotates in the same direction as an input-end gear. The output-side gear of one link and the input-side gear of an adjacent link are used in common, and the rotating shaft of the common gear provides a degree of freedom provided at a joint of the articulated bending mechanism. Such an articulated bending mechanism can be formed with a small size and at a low cost, and can be used to imitate the way a living being shows its feelings and emotions.

TECHNICAL FIELD

[0001] The present invention relates to an articulated robot comprisinga plurality of joint actuators, and, more particularly, to a leggedmobile robot using an ambulatory animal, such as a human being, an ape,or a dog, as a model.

[0002] Even more particularly, the present invention relates to a leggedmobile robot comprising a bending portion that is formed by a pluralityof joints, such as fingers, a tail, a neck, or a nose, and anarticulated bending mechanism thereof. Still more particularly, thepresent invention relates to a legged mobile robot whose articulatedbending mechanism is small and low in cost and which imitates the way aliving being shows its emotions and feelings, and the articulatedbending mechanism thereof.

BACKGROUND ART

[0003] A robot is a mechanical device which moves like a human being bymaking use of electrical and magnetic actions. The term “robot” is saidto be derived from the Slavic word “ROBOTA” (slavish machine). In ourcountry, the widespread use of robots began at the end of the 1960s,many of which were industrial robots, such as manipulators andconveyance robots, used, for example, for the purpose of achievingautomatic industrial operations in factories without humans inattendance.

[0004] Installation-type robots, such as robots having arms, which areused by being implanted at a particular place, function only in fixed,limited working spaces for carrying out parts assembly/sorting or thelike. In contrast, mobile robots can function in unlimited workingspaces, so that they can freely move in predetermined paths or pathlessareas in order to perform in place of human beings a predetermined or adesired human task, or to provide various wide-ranging services in placeof living beings such as human beings or dogs. Of the mobile robots,legged mobile robots are unstable compared to crawler robots and robotswith tires, so that it becomes difficult to control their posture andwalking. However, legged mobile robots are excellent robots in that theycan walk/run flexibly regardless of whether or not the ground isleveled, such as going up and down steps or a ladder or going overobstacles.

[0005] In recent years, advances have been made in the research anddevelopment of legged mobile robots such as humanoid robots which aredesigned using as a model the motion and mechanism of the body of ananimal, such as a human being, which moves erect using two feet. Thereare increasing expectations for putting such robots into practical use.For example, Sony Corporation has presented a bipedal-walking humanoidrobot “SDR-3X” on November 25.

[0006] Legged mobile robots may be used to help carry out or to carryout in place of human beings various difficult operations, such as inindustrial tasks or production work. They carry out in place of humanbeings dangerous or difficult operations for human beings, such asmaintenance work at nuclear power plants, thermal power plants, orpetrochemical plants, parts transportation/assembly operations inmanufacturing plants, cleaning in tall buildings, rescuing of people atplaces where there is a fire, etc.

[0007] Legged mobile robots may also be used for purposes closelyrelated to life, such as for “living together” purposes or entertainmentpurposes, instead of helping human beings carry out a task. This type ofrobot imitates the way a living being fully shows its feelings andemotions using the four limbs or a movement mechanism of a leggedwalking animal which is relatively highly intelligent, such as a humanbeing or a dog (pet). Legged mobile robots are required not only tofaithfully execute a previously input behavior pattern, but also torespond vividly and dynamically to the words and behavior of, forexample, a person (such as when praising, scolding, or hitting).

[0008] When legged mobile robots comprise, for example, uniform movablelegs that are mounted to the left and right portions of the trunk, theycan do the minimum work in the living space of human beings. In orderfor the legged mobile robots to function and behave in a moresophisticated manner, such as holding an object or handling a particularobject in a working space, or making gestures or dancing using the upperhalf of the body, it is necessary to make the upper limbs move, and,desirably, to install an articulated bending mechanism for moving thefinger tips even at the hands that are provided at the ends of the upperlimbs.

[0009] A mechanism which can bend at a plurality of joints, such as thetail that many quadrupedal walking animals have, the neck of a giraffe,or the nose of an elephant, is very useful in making the robot imitatethe way a living being shows its feelings and emotions.

[0010] However, in general, an articulated bending mechanism is designedand manufactured by disposing an actuator for every movable shaft.Therefore, for a member of a robot which is elongated like a finger andhas very small intervals between links connecting each joint, the jointmechanism becomes large and complicated, so that the joint mechanismdoes not look like a finger.

[0011] An example of an elongated articulated mechanism is a bendingmechanism used in, for example, an endoscope. However, this type ofbending mechanism using a wire has difficulty generating a large drivingforce and is not suited for mass production because expensive structuralmembers are used to assemble it.

DISCLOSURE OF INVENTION

[0012] It is an object of the present invention to provide an excellentlegged mobile robot comprising a bending portion that is formed by aplurality of joints, such as fingers, a tail, a neck, or a nose; and anarticulated bending mechanism thereof.

[0013] It is another object of the present invention to provide anexcellent legged mobile robot whose articulated bending mechanism issmall and low in cost and which can be used to imitate the way a livingbeing shows its emotions and feelings; and the articulated bendingmechanism.

[0014] In view of the above-described problems, according to a firstaspect of the present invention, there is provided an articulatedbending mechanism for a legged mobile robot having at least movablelegs, which is formed by connecting links which rotatably support aplurality of gears including input-side gears and output-side gears byengaging the gears.

[0015] Here, the articulated bending mechanism may be constructed sothat each link rotatably supports an odd number of gears by engaging thegears, and an output-end gear rotates in the same direction as aninput-end gear.

[0016] The articulated bending mechanism may be constructed so that theoutput-side gear of one link and the input-side gear of an adjacent linkare used in common, and the rotating shaft of the common gear provides adegree of freedom provided at a joint of the articulated bendingmechanism.

[0017] The articulated bending mechanism may further comprise a drivesection for applying rotational force to the input-side gear at abottommost link, wherein, as the rotational force is applied by thedrive section, bending occurs at a joint between each link in a certaindirection.

[0018] Therefore, the articulated bending mechanism of the first aspectof the present invention easily generates a large driving force comparedto a bending mechanism using a wire. In addition, since the articulatedbending mechanism of the first aspect of the present invention can beassembled using only inexpensive structural members, it is possible toachieve mass production. Further, by forming the articulated bendingmechanism small and at a low cost, it can be used in the legged mobilerobot to imitate the way a living being shows its feelings and emotions.

[0019] The drive section may have a clutch mechanism for allowing theinput-side gear of the bottommost link to rotate freely by disengagingthe rotating shaft when a rotational opposing force equal to or greaterthan a predetermined value is applied to the drive section from theinput-side gear of the bottommost link. Therefore, even if an abnormalopposing force is exerted upon the articulated bending mechanism, byallowing free rotation of the gear, the opposing force is nottransmitted to a motor, thereby making it possible to prevent breakageof the device.

[0020] The articulated bending mechanism may further comprise an endportion which engages the output-side gear of the link at a frontmostend in order to prevent idle rotation of the gears supported by therespective links, so that bending at a joint between each link in acertain direction as each gear rotates is ensured.

[0021] The articulated bending mechanism may be constructed so that eachlink has a restricting section which, in order to prevent rotation in areverse direction at a joint between adjacent links, comes into contactwith its adjacent link in a predetermined rotating position at the jointfor restricting rotation.

[0022] The articulated bending mechanism according to the first aspectof the present invention may be used as, for example, fingers of thelegged mobile robot. In such a case, the sizes of the links or thedistances between joints of the fingers are adjusted according to thenumber of gears accommodated in each link.

[0023] In other words, when the fingers of the hands are formed usingthe articulated bending mechanism, it is not necessary to dispose anactuator for each movable shaft, so that members like the fingers whichare elongated and which have very small intervals between linksconnecting each joint can be designed and manufactured with small sizes.

[0024] The articulated bending mechanism of the first aspect of thepresent invention easily generates a large driving force compared to abending mechanism using a wire. In addition, since the articulatedbending mechanism of the first aspect of the present invention can beassembled using only inexpensive structural members, it is possible toachieve mass production.

[0025] The articulated bending mechanism of the first aspect of thepresent invention may be used as a neck of the legged mobile robot.

[0026] More specifically, when the neck of a giraffe is formed using thearticulated bending mechanism, it is not necessary to dispose anactuator for each movable shaft, and a member which is elongated likethe neck of a giraffe and which has very small intervals between thelinks connecting each joint can be designed and manufactured with asmall size. In addition, compared to the case where a bending mechanismusing a wire is used, a large driving force can be easily generated.Further, since the articulated bending mechanism of the first aspect ofthe present invention can be assembled using only inexpensive structuralmembers, it is possible to achieve mass production.

[0027] The articulated bending mechanism of the first aspect of thepresent invention may be used as a nose of the legged mobile robot.

[0028] More specifically, when the nose of an elephant is formed usingthe articulated bending mechanism, it is not necessary to dispose anactuator for each movable shaft, and a member which is elongated likethe nose of an elephant and which has very small intervals between thelinks connecting each joint can be designed and manufactured with asmall size. In addition, compared to the case where a bending mechanismusing a wire is used, a large driving force can be easily generated.Further, since the articulated bending mechanism of the first aspect ofthe present invention can be assembled using only inexpensive structuralmembers, it is possible to achieve mass production.

[0029] The articulated bending mechanism of the first aspect of thepresent invention may be used as a tail of the legged mobile robot.

[0030] More specifically, when the tail of a lizard is formed using thearticulated bending mechanism, it is not necessary to dispose anactuator for each movable shaft, and a member which is elongated likethe tail of a lizard and which has very small intervals between thelinks connecting each joint can be designed and manufactured with asmall size. In addition, compared to the case where a bending mechanismusing a wire is used, a large driving force can be easily generated.Further, since the articulated bending mechanism of the first aspect ofthe present invention can be assembled using only inexpensive structuralmembers, it is possible to achieve mass production.

[0031] According to a second aspect of the present invention, there isprovided a legged mobile robot having at least movable legs, whichcomprises an articulated bending mechanism which is formed by connectinglinks which rotatably support a plurality of gears including input-sidegears and output-side gears by engaging the gears.

[0032] The legged mobile robot may be constructed so that each link ofthe articulated bending mechanism rotatably supports an odd number ofgears by engaging the gears, and an output-end gear rotates in the samedirection as an input-end gear.

[0033] The legged mobile robot may be constructed so that theoutput-side gear of one link and the input-side gear of an adjacent linkare used in common, and the rotating shaft of the common gear provides adegree of freedom provided at a joint of the articulated bendingmechanism.

[0034] The legged mobile robot may further comprise a drive section forapplying rotational force to the input-side gear at a bottommost link,wherein the articulated bending mechanism is constructed so that, as therotational force is applied by the drive section, bending occurs at ajoint between each link.

[0035] Therefore, the articulated bending mechanism used in the leggedmobile robot of the second aspect of the present invention easilygenerates a large driving force compared to a bending mechanism using awire. In addition, since the articulated bending mechanism of thepresent invention can be assembled using only inexpensive structuralmembers, it is possible to achieve mass production. Further, by formingthe articulated bending mechanism small and at a low cost, it can beused in the legged mobile robot to imitate the way a living being showsits feelings and emotions.

[0036] The drive section may have a clutch mechanism for allowing theinput-side gear of the bottommost link to rotate freely by disengagingthe rotating shaft when a rotational opposing force equal to or greaterthan a predetermined value is applied to the drive section from theinput-side gear of the bottommost link. Therefore, even if an abnormalopposing force is exerted upon the articulated bending mechanism, byallowing free rotation of the gear, the opposing force is nottransmitted to a motor, thereby making it possible to prevent breakageof the device.

[0037] The articulated bending mechanism of the present invention mayfurther comprise an end portion which engages the output-side gear ofthe link at a frontmost end in order to prevent idle rotation of thegears supported by the respective links, so that bending at a jointbetween each link in a certain direction as each gear rotates isensured.

[0038] Each link may have a restricting section which, in order toprevent rotation in a reverse direction at a joint between adjacentlinks, comes into contact with its adjacent link in a predeterminedrotating position at the joint for restricting rotation.

[0039] In the legged mobile robot of the second aspect of the presentinvention, the articulated bending mechanism may be used as, forexample, fingers. In such a case, the sizes of the links or thedistances between joints of the fingers are adjusted according to thenumber of gears accommodated in each link. In other words, when thefingers of the hands are formed using the articulated bending mechanism,it is not necessary to dispose an actuator for each movable shaft, sothat members which are elongated like the fingers and which have verysmall intervals between links connecting each joint can be designed andmanufactured with small sizes.

[0040] In the legged mobile robot of the second aspect of the presentinvention, the articulated bending mechanism may be used as a neck. Morespecifically, when the neck of a giraffe is formed using the articulatedbending mechanism, it is not necessary to dispose an actuator for eachmovable shaft, and a member which is elongated like the neck of agiraffe and which has very small intervals between the links connectingeach joint can be designed and manufactured with a small size.

[0041] In the legged mobile robot of the second aspect of the presentinvention, the articulated bending mechanism may be used as a nose. Morespecifically, when the nose of an elephant is formed using thearticulated bending mechanism, it is not necessary to dispose anactuator for each movable shaft, and a member which is elongated likethe nose of an elephant and which has very small intervals between thelinks connecting each joint can be designed and manufactured with asmall size.

[0042] In the legged mobile robot of the second aspect of the presentinvention, the articulated bending mechanism may be used as a tail. Morespecifically, when the tail of a lizard is formed using the articulatedbending mechanism, it is not necessary to dispose an actuator for eachmovable shaft, and a member which is elongated like the tail of a lizardand which has very small intervals between the links connecting eachjoint can be designed and manufactured with a small size.

[0043] Further objects, features and advantages of the present inventionwill become apparent from the following description of a preferredembodiment with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044]FIG. 1 is a front view showing a state in which an articulatedbending mechanism 1 of an embodiment of the present invention isextended substantially in a straight line.

[0045]FIG. 2 is a side view showing the state in which the articulatedbending mechanism 1 of the embodiment of the present invention isextended substantially in a straight line.

[0046]FIG. 3 is a perspective view showing the state in which thearticulated bending mechanism 1 of the embodiment of the presentinvention is extended substantially in a straight line.

[0047]FIG. 4 is a front view showing a state in which the articulatedbending mechanism 1 of the embodiment of the present invention is bent.

[0048]FIG. 5 is a side view showing the state in which the articulatedbending mechanism 1 of the embodiment of the present invention is bent.

[0049]FIG. 6 is a perspective view showing the state in which thearticulated bending mechanism 1 of the embodiment of the presentinvention is bent.

[0050]FIG. 7 shows a link 11 in six side views, in sectional view, andin perspective view.

[0051]FIG. 8 is an exploded view of the parts of the link 11.

[0052]FIG. 9 is an assembly diagram of the link 11.

[0053]FIG. 10 shows a state in which a link 16 is linked to an adjacentlink 17.

[0054]FIG. 11 shows a state in which the link 16 is linked to theadjacent link 17.

[0055]FIG. 12 shows a state in which the link 16 is linked to theadjacent link 17.

[0056]FIG. 13 shows an end portion 18 in six side views, in sectionalview, and in perspective view.

[0057]FIG. 14 shows an example in which a fist is formed using thearticulated bending mechanism 1 of the embodiment as fingers.

[0058]FIG. 15 shows an example in which a robot of a lizard is formedusing the articulated bending mechanism 1 of the embodiment as a tail.

[0059]FIG. 16 shows an example in which a robot of a giraffe is formedusing the articulated bending mechanism 1 of the embodiment as a neck.

[0060]FIG. 17 shows an example in which a robot of an elephant is formedusing the articulated bending mechanism 1 of the embodiment as a nose.

BEST MODE FOR CARRYING OUT THE INVENTION

[0061] Hereunder, a description of an embodiment of the presentinvention will be given in detail with reference to the drawings.

[0062]FIGS. 1, 2, and 3 are a front view, a side view, and a perspectiveview, respectively, showing a state in which an articulated bendingmechanism 1 of an embodiment of the present invention is extendedsubstantially in a straight line. Similarly, FIGS. 4, 5, and 6 are afront view, a side view, and a perspective view, respectively, showing astate in which the articulated bending mechanism 1 is bent.

[0063] As shown in each figure, the articulated bending mechanism 1comprises seven links 11 to 17, which are linked in series, and an endportion 18, which is linked to the terminal end of the linked links. Adrive unit 20 for providing driving force for bending and extending thearticulated bending mechanism 1 to the articulated bending mechanism 1is mounted to the other end of the linked links.

[0064] The drive unit 20 comprises a motor 21 for producing rotationalmotion by an electromagnetic action, a pinion 22 integrally mounted tothe rotating shaft of the motor 21, a worm gear 23 which engages thepinion 22 to change the direction of the rotating shaft to an orthogonaldirection, and four gears 24 to 27 which transmit rotational force fromthe worm gear 23 to the articulated bending mechanism 1 while reducingthe speed at a predetermined speed reduction ratio.

[0065] The links 11 to 17 of the articulated bending mechanism 1 eachrotatably accommodate three or an odd number of gears. Adjacent gearsengage each other. By transmitting the rotational force by the oddnumber of gears, the directions of rotation of an input-side gear and anoutput-side gear can be made the same. By using the input-side gear ofone link as the output-side gear of an adjacent link, a joint having thedegrees of freedom that is provided around the rotating shaft of thegear that is used in common is formed.

[0066] The link 11 rotatably supports three gears 31, 32, and 33 inseries. By engaging the gear 31, disposed at one end, with the outputgear 27 of the drive unit 20, rotational driving force is input to thegear 31. The rotating shaft of the gear 31 forms the zeroth joint of thearticulated bending mechanism 1. The rotational driving force istransmitted to the gear 32 engaging the gear 31 in order to transmitrotational force acting in the same direction to the gear 33.

[0067] The link 12 rotatably supports three gears, the gear 33 and gears34 and 35, in series. The gear 33, disposed at one end, is used incommon by the adjacent link 11. The rotating shaft of the gear 33 formsthe first joint of the articulated bending mechanism 1. The rotationalforce applied to the gear 33 is transmitted to the gear 34 engaging thegear 33 in order to transmit rotational force acting in the samedirection to the gear 35.

[0068] The link 13 rotatably supports three gears, the gear 35 and gears36 and 37, in series. The gear 35, disposed at one end, is used incommon by the adjacent link 12. The rotating shaft of the gear 35 formsthe second joint of the articulated bending mechanism 1. The rotationalforce applied to the gear 35 is transmitted to the gear 36 engaging thegear 35 in order to transmit rotational force acting in the samedirection to the gear 37.

[0069] The link 14 rotatably supports three gears, the gear 37 and gears38 and 39, in series. The gear 37, disposed at one end, is used incommon by the adjacent link 13. The rotating shaft of the gear 37 formsthe third joint of the articulated bending mechanism 1. The rotationalforce applied to the gear 37 is transmitted to the gear 38 engaging thegear 37 in order to transmit rotational force acting in the samedirection to the gear 39.

[0070] The link 15 rotatably supports three gears, the gear 39 and gears40 and 41, in series. The gear 39, disposed at one end, is used incommon by the adjacent link 14. The rotating shaft of the gear 39 formsthe fourth joint of the articulated bending mechanism 1. The rotationalforce applied to the gear 39 is transmitted to the gear 40 engaging thegear 39 in order to transmit rotational force acting in the samedirection to the gear 41.

[0071] The link 16 rotatably supports three gears, the gear 41 and gears42 and 43, in series. The gear 41, disposed at one end, is used incommon by the adjacent link 15. The rotating shaft of the gear 41 formsthe fifth joint of the articulated bending mechanism 1. The rotationalforce applied to the gear 41 is transmitted to the gear 42 engaging thegear 41 in order to transmit rotational force acting in the samedirection to the gear 43.

[0072] The link 17 rotatably supports three gears, the gear 43 and gears44 and 45, in series. The gear 43, disposed at one end, is used incommon by the adjacent link 16. The rotating shaft of the gear 43 formsthe sixth joint of the articulated bending mechanism 1. The rotationalforce applied to the gear 43 is transmitted to the gear 44 engaging thegear 43 in order to transmit rotational force acting in the samedirection to the gear 45.

[0073] The end portion 18 is mounted to the other end of the link 17. Asdescribed later, a toothed portion 18A engaging the terminal gear 45 isformed at the inner wall of the end portion 18. Therefore, byterminating the output-side gear 45 of the link 17 by engaging it withthe toothed portion 18A of the end portion 18, it is possible to applythe rotational force which is applied to the fifteen gears 31 to 45 tothe respective links 11 to 17 without idle rotation of the gears 31 to45 around respective rotating shafts 31A to 45A.

[0074] For example, in the link 11, as shown in FIG. 5, when rotationalforce acting in a clockwise direction with respect to the plane of thefigure applied to the gear 31 is transmitted to the gear 33 through thegear 32, the gears 31 to 33 do not end up rotating idly. Instead, aforce which rotates the link 11 clockwise in the plane of the figure atthe first joint defined by the rotating shaft of the gear 31 isgenerated.

[0075] In the link 12, as shown in FIG. 5, when rotational force actingin a clockwise direction with respect to the plane of the figure appliedto the gear 33 is transmitted to the gear 35 through the gear 34, thegears 33 to 35 do not end up rotating idly. Instead, a force whichrotates the link 12 clockwise in the plane of the figure at the secondjoint defined by the rotating shaft of the gear 33 is generated.

[0076] In the link 13, as shown in FIG. 5, when rotational force actingin a clockwise direction with respect to the plane of the figure appliedto the gear 35 is transmitted to the gear 37 through the gear 36, thegears 35 to 37 do not end up rotating idly. Instead, a force whichrotates the link 13 clockwise in the plane of the figure at the thirdjoint defined by the rotating shaft of the gear 35 is generated.

[0077] In the link 14, as shown in FIG. 5, when rotational force actingin a clockwise direction with respect to the plane of the figure appliedto the gear 37 is transmitted to the gear 39 through the gear 38, thegears 37 to 39 do not end up rotating idly. Instead, a force whichrotates the link 14 clockwise in the plane of the figure at the fourthjoint defined by the rotating shaft of the gear 37 is generated.

[0078] In the link 15, as shown in FIG. 5, when rotational force actingin a clockwise direction with respect to the plane of the figure appliedto the gear 39 is transmitted to the gear 41 through the gear 40, thegears 39 to 41 do not end up rotating idly. Instead, a force whichrotates the link 15 clockwise in the plane of the figure at the fifthjoint defined by the rotating shaft of the gear 39 is generated.

[0079] In the link 16, as shown in FIG. 5, when rotational force actingin a clockwise direction with respect to the plane of the figure appliedto the gear 41 is transmitted to the gear 43 through the gear 42, thegears 41 to 43 do not end up rotating idly. Instead, a force whichrotates the link 16 clockwise in the plane of the figure at the sixthjoint defined by the rotating shaft of the gear 41 is generated.

[0080] In the link 17, as shown in FIG. 5, when rotational force actingin a clockwise direction with respect to the plane of the figure appliedto the gear 43 is transmitted to the gear 45 through the gear 44, thegears 43 to 45 do not end up rotating idly. Instead, a force whichrotates the link 17 clockwise in the plane of the figure at the seventhjoint defined by the rotating shaft of the gear 43 is generated.

[0081] A clutch mechanism for disengaging the rotating shaft when arotational opposing force equal to or greater than a predetermined valueis applied to the output-end gear 27 of the drive unit 20 isincorporated in the output-end gear 27. Therefore, even if an abnormalopposing force is applied to the articulated bending mechanism 1, it ispossible to prevent breakage of the device because the opposing force isnot transmitted to the motor 21 due to disengagement of the gear 27. Inthis case, in the articulated bending mechanism 1, the first jointdefined by the rotating shaft of the gear 31 is disengaged.

[0082]FIG. 7 shows the link 11 in six side views, in sectional view, andin perspective view. FIG. 8 is an exploded view of the parts of the link11. FIG. 9 is an assembly diagram of the link 11. Although the otherlinks 12 to 17 are not shown, it is to be understood that they havesubstantially the same structures as the link 11.

[0083] As shown in FIGS. 7, 8, and 9, in the link 11, a top plate 11Aand a bottom plate 11B are supported substantially in parallel by walls11C and 11D with a sufficient gap for accommodating the gears 31 to 33being maintained between the top plate 11A and the bottom plate 11B.

[0084] Three openings 11E, 11F, and 11G and three openings 11E′, 11F′,and 11G′, which oppose the respective openings 11E, 11F, and 11G, forinserting the rotating shafts 31A, 32A, and 33A of the respective gears31 to 33 are formed in the top plate 11A and the bottom plate 11B,respectively.

[0085] By disposing the gears 31 to 33 in series between the top plate11A and the bottom plate 11B, and passing the respective rotating shafts31A, 32A, and 33A through them, they are accommodated in the spacebetween the top plate 11A and the bottom plate 11B of the link 11 withthe adjacent gears engaging each other.

[0086] The rotational force applied to the input-side gear 31 istransmitted to the adjacent gear 32 as rotational force acting in theopposite direction. This rotational force is transmitted to theoutput-side gear 33 adjacent the gear 32 as rotational force acting in adirection opposite to the direction of the rotational force applied tothe gear 32, that is, in the same direction as the original direction.This rotational force is output to the following link 12. The number ofgears accommodated inside the one link 11 is not limited to three. Aslong as the number of gears is an odd number of gears, a rotationalforce acting in the same direction as the rotational force at the inputside can be output.

[0087] Steps 11A′ and 11B′ having about the same thicknesses as therespective top plate 11A and bottom plate 11B are formed atsubstantially the centers of the top plate 11A and the bottom plate 11B,respectively, so that the width of the output-side half of the link 11is smaller than that of the input-side half of the link 11. Therefore,by inserting the output-side portions of the top plate 11A and bottomplate 11B of the link 11 into the gap between the input-side portions ofa top plate 12A and a bottom plate 12B of the link 12 adjacent the link11 (see FIGS. 10 and 11), the adjacent links 11 and 12 can be linkedtogether.

[0088] The wall 11C protrudes from foot prints of the top plate 11A andthe bottom plate 11B. In the case where the left and right edges of thewall 1C are linked to the adjacent link and the linked links areextended in a straight line, they can function as stoppers which preventfurther bending at the corresponding joint by coming into contact withthe edges of the wall of the other link. (This is described later.)

[0089] FIGS. 10 to 12 shows a state in which the link 16 is linked tothe adjacent link 17. FIG. 10 shows a state in which the links 16 and 17are extended in a straight line. FIG. 11 shows a state in which the link17 is rotated with respect to the link 16. FIG. 12 shows a state inwhich the link 17 is further rotated with respect to the link 16.

[0090] As shown in FIGS. 10 to 12, the adjacent links 11 and 12 arelinked so that output-side openings 16G and 16G′ of the link 16 andrespective input-side openings 17E and 17E′ of the link 12 coincide. Insuch a state, the output-side gear 43 of the link 16 and the rotatingshaft 43A thereof can be used as the input-side gear of the link 15 andthe rotating shaft thereof, respectively. Here, the rotating shaft 43Aforms the sixth joint of the articulated bending mechanism 1.

[0091] The method of assembling the adjacent links shown in FIGS. 10 to12 are also used for assembling the other adjacent links, the links 11and 11, the links 12 and 13, the links 13 and 14, the links 14 and 15,and the links 15 and 16.

[0092] With the adjacent links 16 and 17 being extended in a straightline in the longitudinal direction as shown in FIG. 10, clockwiserotational force is applied to the input-side gear 41 of the link 16.This rotational force is transmitted as counterclockwise rotationalforce to the adjacent gear 42, and is further transmitted to theoutput-side gear 43 as rotational force acting in the oppositedirection, that is, in the clockwise direction. The gear 43 is used asthe input-side gear of the link 17, and the rotating shaft 43A forms thesixth joint of the articulated bending mechanism 1. Therefore, byrotating the gear 41 clockwise, a rotational force acting in a clockwisedirection in the plane of the figure is applied to the sixth joint, and,following this, the link 17 rotates clockwise with the rotating shaft43A as the center as shown in FIG. 11.

[0093] Originally, such rotational force is similarly successivelytransmitted from the first joint, the second joint, the third joint,etc., so that the articulated bending mechanism 1 as a whole becomesbent as shown in FIGS. 4 to 6. By further rotating the gear 41 clockwiseas shown in FIG. 12, the link 17 continues to further rotate clockwisewith the rotating shaft 43A as the center.

[0094] With the adjacent links 16 and 17 being extended in a straightline in the longitudinal direction as shown in FIG. 10, the right edgeof a wall 16C of the link 16 is in contact with the left edge of a wall17C of the link 17, so that the movable angle at the sixth joint isrestricted. For this reason, the articulated bending mechanism 1 can beprevented from further bending in the counterclockwise direction fromits straight-line state when the link 17 tries to rotate further in thecounterclockwise direction around the first joint, or the rotating shaft43A.

[0095] Up to now, the structure of the links and the structure forconnecting a link to an adjacent link have been described. By similarlylinking the seven links 11 to 17 having the same structure, thearticulated bending mechanism 1 of the embodiment can be formed with anelongated bending structure. In addition, as already mentioned, the endportion 18 is mounted to an end of the articulated bending mechanism 1.

[0096]FIG. 13 shows the end portion 18 in six side views, in sectionalview, and in perspective view. As shown in cross section in FIG. 12, thetoothed portion 18A engaging the terminal gear 45 is formed at the innerwall of the end portion 18.

[0097] The gear 45 of the link 17 can be terminated by engaging theoutput-side gear 45 with the toothed portion 18A of the end portion 18.FIGS. 10 to 12 also show a state in which the gear 45 is terminated bymounting the end portion 18 to the end of the link 17. By terminatingthe output-side gear 45, it is possible to apply the rotational forceapplied to the fifteen gears 31 to 45 to the links 11 to 17 without idlerotation of the gears 31 to 45 around the respective rotating shafts 31Ato 45A. As a result, when the rotational force of the motor 21 istransmitted to the articulated bending mechanism 1 through the pinion22, the worm gear 23, and the gears 24 to 27, the articulated bendingmechanism 1 can be properly bent as shown in FIGS. 4 to 6 without idlerotation of the gears 31 to 45.

[0098] Next, a description of examples of application of theabove-described articulated bending mechanism 1 will be given.

[0099] As already mentioned in the “Background Art,” when the leggedmobile robot comprises, for example, uniform movable legs that aremounted to the left and right portions of the trunk, it can do theminimum work in the living space of human beings. In order for thelegged mobile robot to function and behave in a more sophisticatedmanner, such as holding an object or handling a particular object in aworking space, or making gestures or dancing using the upper half of thebody, it is desirable to install fingertips at the upper limbs or at thehands at the ends of the upper limbs. A mechanism which can bend at aplurality of joints, such as the tail that many quadrupedal animalshave, the neck of a giraffe, or the nose of an elephant, is very usefulin making the robot imitate the way a living being shows its feelingsand emotions.

[0100] However, in general, a related articulated bending mechanism isdesigned and manufactured by disposing an actuator for each movableshaft. Therefore, for a member of a robot which is elongated like afinger or which has very small intervals between links connecting eachjoint, the mechanism becomes large and complicated.

[0101]FIG. 14 shows an example in which a fist is formed by using thearticulated bending mechanism 1 of the embodiment as fingers.

[0102] As shown in FIG. 14, in a hand 50, five articulated bendingmechanisms 52 to 56, forming the thumb, the index finger, the middlefinger, the third finger, and the little finger, are mounted to a frame51, forming the back of the hand. The palm side of the frame 51 is thebending direction.

[0103] It is desirable to determine the ratios between the lengths andthicknesses of the articulated bending mechanism 52 to 56 by carefullyconsidering the purposes and functions of the thumb, index finger,middle finger, ring finger, and thumb, and the hand of an actual person.

[0104] The articulated bending mechanism 52 to 56 each comprise threelinks and one end portion, and have three joints. It is desirable foreach bottom link forming the part of the finger to the first joint to belonger than the other links in terms of its function and the structureof the palm of the hand. In this case, by increasing the number of gearsaccommodated in each link from three to five, each link can be made longwith the same thicknesses.

[0105] When the fingers of the hand are formed using the articulatedbending mechanism 1 of the embodiment as shown in FIG. 14, it is notnecessary to dispose an actuator for each movable shaft, so that memberslike the fingers which are elongated and which have very small intervalsbetween links connecting each joint can be designed and manufacturedwith small sizes.

[0106] When a hand is formed using the articulated bending mechanism 1of the embodiment, a large driving force is easily generated compared tothe case where a bending mechanism using a wire is used. In addition,since the articulated bending mechanism 1 of the embodiment can beassembled using only inexpensive structural members, it is possible toachieve mass production.

[0107]FIG. 15 shows an example in which a robot of a lizard is formedusing the articulated bending mechanism 1 of the embodiment as a tail.

[0108] When the tail of a lizard is formed using the articulated bendingmechanism 1 of the embodiment as shown in FIG. 15, it is not necessaryto dispose an actuator for each movable shaft, so that a member which iselongated like the tail of a lizard and which has very small intervalsbetween links connecting each joint can be designed and manufacturedwith a small size.

[0109] When the tail of a lizard is formed using the articulated bendingmechanism 1 of the embodiment, a large driving force is easily generatedcompared to the case where a bending mechanism using a wire is used. Inaddition, since the articulated bending mechanism 1 of the embodimentcan be assembled using only inexpensive structural members, it ispossible to achieve mass production.

[0110]FIG. 16 shows an example in which a robot of a giraffe is formedusing the articulated bending mechanism 1 of the embodiment as a neck.

[0111] When the neck of a giraffe is formed using the articulatedbending mechanism 1 of the embodiment as shown in FIG. 16, it is notnecessary to dispose an actuator for each movable shaft, so that amember which is elongated like the neck of a giraffe and which has verysmall intervals between links connecting each joint can be designed andmanufactured with a small size.

[0112] When the neck of a giraffe is formed using the articulatedbending mechanism 1 of the embodiment, a large driving force is easilygenerated compared to the case where a bending mechanism using a wire isused. In addition, since the articulated bending mechanism 1 of theembodiment can be assembled using only inexpensive structural members,it is possible to achieve mass production.

[0113]FIG. 17 shows an example in which a robot of an elephant is formedusing the articulated bending mechanism 1 of the embodiment as a nose.

[0114] When the nose of an elephant is formed using the articulatedbending mechanism 1 of the embodiment as shown in FIG. 17, it is notnecessary to dispose an actuator for each movable shaft, so that amember which is elongated like the nose of an elephant and which hasvery small intervals between links connecting each joint can be designedand manufactured with a small size.

[0115] When the nose of an elephant is formed using the articulatedbending mechanism 1 of the embodiment, a large driving force is easilygenerated compared to the case where a bending mechanism using a wire isused. In addition, since the articulated bending mechanism 1 of theembodiment can be assembled using only inexpensive structural members,it is possible to achieve mass production.

[0116] Supplement

[0117] The present invention has been described in detail with referenceto a particular embodiment. However, it is apparent that variousmodifications and substitutions may be made by those skilled in the artwithin a scope not departing from the gist of the present invention.

[0118] The gist of the present invention is not necessarily limited to aproduct called a “robot.” More specifically, as long as the device is amechanical device which moves like a human being by making use ofelectrical and magnetic actions, the present invention may be similarlyapplied to products of other industrial fields, such as toys.

[0119] The point is that the present invention has been disclosed withreference to illustrative forms thereof, so that the description of thespecification is not to be construed in a restrictive sense. In order todetermine the gist of the present invention, one should refer to theclaims.

INDUSTRIAL APPLICABILITY

[0120] The present invention makes it possible to provide an excellentlegged mobile robot comprising a bending portion that is formed by aplurality of joints, such as fingers, a tail, a neck, or a nose; and anarticulated bending mechanism thereof.

[0121] The present invention also makes it possible to provide anexcellent legged mobile robot whose articulated bending mechanism issmall and low in cost and which can be used to imitate the way a livingbeing shows its emotions and feelings; and the articulated bendingmechanism.

[0122] According to the present invention, since the number of actuatorsused in bending and driving at the plurality of joints is reduced, therobot can be formed with a small size and at a low cost. Therefore, thepresent invention can contribute to reducing the cost and size of adevice comprising this type of articulated bending mechanism.

1. An articulated bending mechanism for a legged mobile robot having atleast movable legs, which is formed by connecting links which rotatablysupport a plurality of gears including input-side gears and output-sidegears by engaging the gears.
 2. An articulated bending mechanism for alegged mobile robot according to claim 1, wherein each link rotatablysupports an odd number of gears by engaging the gears, and an output-endgear rotates in the same direction as an input-end gear.
 3. Anarticulated bending mechanism for a legged mobile robot according toclaim 1, wherein the output-side gear of one link and the input-sidegear of an adjacent link are used in common, and wherein the rotatingshaft of the common gear provides a degree of freedom provided at ajoint of the articulated bending mechanism.
 4. An articulated bendingmechanism for a legged mobile robot according to claim 1, furthercomprising a drive section for applying rotational force to theinput-side gear at a bottommost link, wherein, as the rotational forceis applied by the drive section, bending occurs at a joint between eachlink in a certain direction.
 5. An articulated bending mechanism for alegged mobile robot according to claim 4, wherein the drive section hasa clutch mechanism for allowing the input-side gear of the bottommostlink to rotate freely by disengaging the rotating shaft when arotational opposing force equal to or greater than a predetermined valueis applied to the drive section from the input-side gear of thebottommost link.
 6. An articulated bending mechanism for a legged mobilerobot according to claim 1, further comprising an end portion whichengages the output-side gear of the link at a frontmost end in order toprevent idle rotation of the gears supported by the respective links, sothat bending at a joint between each link in a certain direction as eachgear rotates is ensured.
 7. An articulated bending mechanism for alegged mobile robot according to claim 1, wherein each link has arestricting section which, in order to prevent rotation in a reversedirection at a joint between adjacent links, comes into contact with itsadjacent link in a predetermined rotating position at the joint forrestricting rotation.
 8. An articulated bending mechanism for a leggedmobile robot according to claim 1, which is used as fingers of thelegged mobile robot.
 9. An articulated bending mechanism for a leggedmobile robot according to claim 8, wherein the sizes of the links or thedistances between joints of the fingers are adjusted according to thenumber of gears accommodated in each link.
 10. An articulated bendingmechanism for a legged mobile robot according to claim 1, which is usedas a neck of the legged mobile robot.
 11. An articulated bendingmechanism for a legged mobile robot according to claim 1, which is usedas a nose of the legged mobile robot.
 12. An articulated bendingmechanism for a legged mobile robot according to claim 1, which is usedas a tail of the legged mobile robot.
 13. A legged mobile robot havingat least movable legs, which comprises an articulated bending mechanismwhich is formed by connecting links which rotatably support a pluralityof gears including input-side gears and output-side gears by engagingthe gears.
 14. A legged mobile robot according to claim 13, wherein eachlink of the articulated bending mechanism rotatably supports an oddnumber of gears by engaging the gears, and an output-end gear rotates inthe same direction as an input-end gear.
 15. A legged mobile robotaccording to claim 13, wherein, in the articulated bending mechanism,the output-side gear of one link and the input-side gear of an adjacentlink are used in common and the rotating shaft of the common gearprovides a degree of freedom provided at a joint.
 16. A legged mobilerobot according to claim 13, wherein the articulated bending mechanismfurther comprises a drive section for applying rotational force to theinput-side gear at a bottommost link, and wherein, as the rotationalforce is applied by the drive section, bending occurs at a joint betweeneach link.
 17. A legged mobile robot according to claim 16, wherein thedrive section has a clutch mechanism for allowing the input-side gear ofthe bottommost link to rotate freely by disengaging the rotating shaftwhen a rotational opposing force equal to or greater than apredetermined value is applied to the drive section from the input-sidegear of the bottommost link.
 18. A legged mobile robot according toclaim 13, wherein the articulated bending mechanism further comprises anend portion which engages the output-side gear of the link at afrontmost end in order to prevent idle rotation of the gears supportedby the respective links, so that bending at a joint between each link ina certain direction as each gear rotates is ensured.
 19. A legged mobilerobot according to claim 13, wherein each link of the articulatedbending mechanism has a restricting section which, in order to preventrotation in a reverse direction at a joint between adjacent links, comesinto contact with its adjacent link in a predetermined rotating positionat the joint for restricting rotation.
 20. A legged mobile robotaccording to claim 13, wherein the articulated bending mechanism is usedas fingers.
 21. A legged mobile robot according to claim 20, wherein thesizes of the links or the distances between joints of the fingers areadjusted according to the number of gears accommodated in each link. 22.A legged mobile robot according to claim 13, wherein the articulatedbending mechanism is used as a neck.
 23. A legged mobile robot accordingto claim 13, wherein the articulated bending mechanism is used as anose.
 24. A legged mobile robot according to claim 13, wherein thearticulated bending mechanism is used as a tail